[196] I2S: PSEL acquires GPIOs regardless of ENABLE

This anomaly applies to IC Rev. Rev 1, build codes QFAA-B00, QFAB-B00, CIAA-B00.

It was inherited from the previous IC revision Engineering C.

Symptoms

I2S controls GPIO even when I2S is not enabled.

Conditions

When using I2S->PSEL to configure GPIO.

Consequences

GPIO selected for I2S cannot be used for any other peripheral.

Workaround

Do not rely on the pins selected in I2S->PSEL registers being free when I2S->ENABLE is set to DISABLE.

Only set the CONNECT bit in the I2S->PSEL registers to CONNECTED immediately before enabling I2S. When disabling I2S, set the CONNECT bit in the I2S->PSEL registers to DISCONNECTED.